1. Field of the Invention
The present invention relates to the field of integrated circuit manufacture, and more specifically to an improved method and construction for the manufacture of liquid crystal on silicon (xe2x80x9cLCOSxe2x80x9d) display arrays. The predominant current usage of the present inventive improved dummy metal pattern method and apparatus is in the construction of reflective LCOS arrays for projection display devices, wherein it is desirable to keep the surface of the array as flat and flawless as possible.
2. Description of the Background Art
In the construction of light reflective or conductive LCOS arrays there will be areas of one or more metal layers wherein there is no circuitry. This situation may occur within the boundaries of the imaging surfaces of the array, or around the perimeter thereof. A similar situation exists where there is very low density circuitry, which might leave substantial unfilled areas with no circuitry therein on the layer. Wherever such absence of circuitry or low circuitry density occurs, such condition is undesirable, since areas of the surface of the array will not be evenly supported, as compared to the areas above the functional circuitry. Since it is critical that the surface of the array be as flat and uniform as possible, in order to preserve the integrity and quality of the image produced thereby, it is desirable to use some method and/or apparatus for generally uniformly supporting the surface layers even where a lack of circuitry might otherwise provide no support.
It is known in the art to provide xe2x80x9cdummyxe2x80x9d circuitry within such areas. In the prior art, such dummy circuitry has consisted of a regular pattern, which pattern has been largely a matter of individual preference. A typical example of such dummy circuitry is a uniform pattern of stripes. While such regular patterns do somewhat achieve the desired goal of supporting the surface layers, the fact remains that a regular pattern is not alike to the adjacent circuitry, and therefore some substantial difference in the amount and quality of support provided to surface layers continues to exist. It would be desirable to have some method or means for providing support to the surface layers of a reflective LCOS array wherein such support is generally uniform under the entire surface of the array, regardless of whether or not such support is provided by operational circuitry patterns or dummy metal. However, to the inventor""s knowledge no such method or means has existed in the prior art.
Accordingly, it is an object of the present invention to provide a method and apparatus for minimizing the perceptible effects of distortion caused by uneven underlayment of the surface of an LCOS imager.
It is another object of the present invention to provide a method and apparatus for improving the quality of an image produced by a reflective LCOS array.
It is yet another object of the present invention to provide a method and apparatus for producing a reflective LCOS array which can be readily implemented using known manufacturing techniques.
Briefly, a known embodiment of the present invention is an arrangement of metal on unused areas of a metal layer of an LCOS imager wherein such metal closely resembles actual functional nearby circuitry patterns. According to the present inventive method, a pattern of circuitry is chosen to fill otherwise unused areas of a metal layer. A space to be filled by the dummy metal is created by growing a margin around existing circuitry. The dummy metal pattern is then trimmed to fill such space. Then, final adjustments are made to the fill pattern by trimming away slivers of metal, and the like, to conform to the design criteria.
These and other objects and advantages of the present invention will become clear to those skilled in the art in view of the description of modes of carrying out the invention, and the industrial applicability thereof, as described herein and as illustrated in the several figures of the drawing. The objects and advantages listed are not an exhaustive list of all possible advantages of the invention. Moreover, it will be possible to practice the invention even where one or more of the intended objects and/or advantages might be absent or not required in the application.
Further, those skilled in the art will recognize that various embodiments of the present invention may achieve one or more, but not necessarily all, of the above described objects and advantages. Accordingly, the listed advantages are not essential elements of the present invention, and should not be construed as limitations.